1. Field of the Invention
The present invention relates to a cooling structure in an electric vehicle for cooling batteries and/or an electric part cooling air from a cooling fan.
2. Description of the Related Art
In a conventional electric vehicle including batteries disposed below a floor panel, electric parts such as a motor controller, a PDU and the like are disposed in an engine compartment or other vehicle compartment, and correspondingly a cooling fan for cooling the batteries and a cooling fan for cooling the electric parts are provided separately.
If the batteries and the electric parts are disposed in different places as described above, a plurality of cooling fans are required. Therefore, if the batteries and the electric part were mounted within a battery box and they are cooled collectively by a common cooling fan, the number of cooling fans can be reduced.
In this regard the effect of cooling air on the batteries each having a battery case made of a synthetic resin with a large thermal resistance maybe less enhanced, if the flow speed of the cooling air is high. Instead, it is desirable that the cooling air having a low flow rate be applied uniformly to all the batteries. On the other hand, the electric parts have a casing or cooling fins made of a metal which has a far smaller thermal resistance as compared with the battery cases. For this reason, a smaller flow amount of the cooling air is required, and the cooling effect achieved by cooling air having a high flow rate is appropriate for the electric parts.
If the cooling air obtained utilizing the outside air as it is, is applied directly to a delicate electric part, there is a possibility that an adverse effect may be exerted to the reliability and durability of the electric part due to dusts and water contained-in the cooling air. It can be conceived to filter the outside air to remove the dusts and water. However, to carry out such a treatment requires a special filter, resulting in a problem of cost increase.